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  <script>
    //  var arr = []
    // var arr = new Array()

    // var obj = {}
    // var obj = new Object()

    var a = 123  // 变量

    var obj = {
      a: '123'  // a 属性
    }

    function b() {  // 函数
      console.log('vvv')
    }
    b()

    var obj = {
      fn: function() {}  // 方法
    }
  </script>
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